Despite ubiquitous application, conventional CMOS image sensors suffer from a number of limitations. First, the linear relationship between photon strikes and pixel value yields a relatively small dynamic range in which a pixel quickly reaches saturation under brightening conditions. Additionally, because the maximum number of detectable photon strikes is proportional to pixel size, the pixel footprint is dictated by the dynamic range required in a given application and does not scale with shrinking process geometries. In high-end digital cameras, like DSLRs (digital single-lens reflex) for example, the photo diode tends to be four or more micrometers at each edge in order to achieve a reasonable dynamic range, consuming an area hundreds or even thousands of times the minimum transistor size permitted by leading logic process geometries.